Surgical guides, from the most rudimentary ones to the most sophisticated, for assisting the operation of replacement the knee joint, are described in the literature and are also widely used in a wide range of daily applications. It is also known that the position of the bony resections must be defined based on the patient's ligament balance to allow a correct functional recovery of the joint. The tibial resection is used to this end as a reference for defining the outer rotation of the femoral prosthetics component.
The most typical system is that based on the intramedullary canal of the femur but this implies possible complications for the patient in particular due to the greater invasiveness of the equipment to use, as well as to a reduced visibility of the equipment support bone, implying greater difficulty in achieving the required accuracy. The weakness of conventional equipment lies above all in the fact that they are still too invasive and as such they may cause complications for the patient. A strict relation therefore exists between the invasiveness of the equipment (especially if not up-to-date) and the frequency and seriousness of complications for patients. This adds up to the consequent poor visibility of the patient's bone during the positioning of the femoral guide that often impairs the critical aspect of obtaining good results in terms of accuracy and repeatability.